Active matrix organic light-emitting diode display device and method for driving the same

Abstract

A method for driving an active matrix organic light-emitting diode (AMOLED) display. The method may be used to digitally drive the AMOLED display in a way that limits the susceptibility of the AMOLED display to certain problems arising out of digital driving techniques, such as image sticking or low display lifetimes. The method involves generating compensation factors corresponding to each pixel of the display and using those compensation factors to control the illumination of the display. The aspects of the method that incorporate the operation point for generating a compensation factor may also be applied to analog driving of AMOLED displays.

What is claimed is: 
     
       1. A method for driving an active matrix organic light-emitting diode (AMOLED) display, the AMOLED display comprising a plurality of organic light-emitting diodes (OLEDs) arranged in a plurality of rows and a plurality of columns; a plurality of pixel circuits each configured to drive an OLED, and arranged in a plurality of rows and a plurality of columns; a scan line for selecting the pixel circuits of each row of pixel circuits and a data line for controlling the pixel circuits of each column of pixel circuits; and a plurality of supply lines connected to the anodes and cathodes of the AMOLED pixels; wherein the method comprises:
 measuring, with an electronic unit, an electrical property of one or more OLEDs, each of the one or more OLEDs being a component of an OLED pixel, each of the OLED pixels having a current efficiency value; 
 calculating, with a processor, a compensation factor against the drift of the current efficiency of the one or more OLED pixels based on the electrical properties measured; 
 adjusting, based on the compensation factor of the one or more OLED pixels, one or more pixel gray values of the one or more OLED pixels, wherein the adjustment of the one or more pixel gray values further depends on an operation point of an OLED in the OLED pixel; 
 applying a data signal to the pixel circuit based on the adjusted pixel gray value; and 
 wherein the adjusted pixel gray value of the OLED pixel is generated based on the amplitude of the current fed to the pixel circuit, and 
 wherein the dependence of the current efficiency on the operation point of the OLED is considered in calculating the compensation factor. 
 
     
     
       2. The method of  claim 1 , wherein the step of measuring, with an electronic unit, an electrical property of one or more OLEDs is performed when the AMOLED display is in a passive state. 
     
     
       3. The method of  claim 1 , wherein a pixel current measurement is taken of an OLED receiving a constant voltage. 
     
     
       4. The method of  claim 1 , wherein the adjusted pixel gray values are determined by an iterative procedure with at least one loop. 
     
     
       5. The method of  claim 1 , wherein the adjusted pixel gray values are determined by a search procedure. 
     
     
       6. The method of  claim 1 , wherein the adjusted pixel gray values are determined by referencing a lookup table including a dependence of a relative degradation of the current efficiency on the operation point of the OLED. 
     
     
       7. The method of  claim 1 , wherein the calculation of an adjusted pixel gray value corresponding to a current frame in a plurality of frames incorporates the value of an adjusted pixel gray value corresponding to a previous frame in the plurality of frames. 
     
     
       8. The method of  claim 1 , wherein each of the adjusted pixel gray values is represented as a binary string having a particular resolution, and wherein the step of adjusting one or more pixel gray values of the one or more OLED pixels comprises processing the original gray values of the one or more OLED pixels with a column driver, and wherein the adjusted pixel gray values have a higher resolution than the original gray values of the one or more OLED pixels. 
     
     
       9. The method of  claim 1 , wherein an accumulated stress value is tracked for one or more OLEDs, and wherein a compensation factor is calculated based on the accumulated stress on the one or more OLEDs. 
     
     
       10. The method of  claim 9 , wherein the compensation factor is calculated such that the accumulated stress on an OLED is more influential in calculating the compensation factor when the accumulated stress is low, and less influential in calculating the compensation factor when the accumulated stress is high.